RV7 bottom & side skin layer order question

[sleeper-319]

Hey all, my exact question is asked (but unanswered) in this very old thread. Copying his words here:

It appears, from the drawings, that the F-776 Fwd Bottom Skin goes UNDER the F-770 Fwd side skins. This would also make sense from the perspective of rain runoff.

However, doing it that way pushes the side skin away from the 704 bulkhead. I think it would also push the side skin away from the firewall, which is the next step in my assembly process. So, if viewed from the front of the aircraft looking aft, the sideskin comes up the 704 bulkhead very nice and flat, then "bends" out to accomodate the bottom skin. This leaves a gap between the side skin and the bulkhead that will be impossible to close.

Given how nicely every other assembly on the RV has gone, this seems strange to me and raised a red flag that I should stop and consult. Can anybody clue me in?

I'm at the same sspot in the build now, and having the same question. Any thoughts or explanation of what you did on yours is appreciated. Thanks.

 

[Ralph Inkster]

Drawing 28, detail D
Side skin should be tucked under belly skin. Diagram could be confusing, note the rear corner of F770, rivet passes through F776 belly, F770 side than F778 aft belly skins.
Any gaps could be filled with Proseal or similar. Do not use any silicone type sealer as will repel paint later.

 

[sleeper-319]

Dwg 28, detail D details the aft end of the F-770 side skin and the F-776 bottom skin.

The section I'm curious about is the junction of the F-770 side skin and the aft rolled edge of the F-772 forward bottom skin and the F704 bulkhead assembly; just at/ahead of the 704 center bulkhead where the wings attach. This area is obscured by the wing root on an assembled plane. So the gap may not be an issue. But here the drawings show the rolled aft edge of the front yard F-772 being under the F-770 side skin (if I'm reading correctly). This makes sense for water shedding, but it leaves a gap of the thickness of the F-772 fwd bottom skin beteween the side skin and the bulkhead assembly. Like the other poster from 08, I'm used to things fitting nicely, and this gap just makes me suspicious I've missed something or done something wrong.

 

[D-Dubya]

Hang on, I've gotten lost in the description. F-776 is the CENTER bottom skin (not the forward), and the 704 bulkhead is where the wing spar passes through. Drawing 28 is the correct drawing to reference, but Detail D is further back at the rear of the baggage area. So which area is the focus of this discussion? Is it the forward area and bottom skin (where your feet go)?

 

[D-Dubya]

The side skin comes over the top of the forward bottom skin, just like it will shed rain. I tried to find a picture that shows the area you're talking about, but this was the best I could do. I took this when I was aligning the gear leg fairings, but it shows those skins and where the 704 bulkhead is. See if this helps...

 

[sleeper-319]

Yes, you have it correct. I've attached a pic of the section I'm talking about.

Where the red arrow is, the rolled edge of the bottom skin fits under the side skin, and the thickness of the bottom skin leaves a gap between the side skin and the bulkhead. See the arrow in the second pic.

 

[D-Dubya]

It looks like you have it assembled correctly, but I honestly don't remember if the skin on mine has a little "crease" there where it got riveted in or if I did anything to lessen that transition. It was over twenty years ago for me when I was at that stage and I can't see it on an assembled aircraft. Hopefully someone that just passed this stage will chime in.

 

[sleeper-319]

Got it. Thanks.

 

[Ralph Inkster]

You won’t even notice the overlap after it’s riveted. That area is hidden by the wing fairings eventually.
If you live in a cool area, you will be looking for ways to seal air drafts coming in around your spar openings. This area will be where you will be sealing them.